The Windy City is the latest U.S. city to enact legislation that mandates building energy benchmarking and disclosure for owners of large commercial and residential buildings. The ordinance was introduced in June 2013 and passed city council vote on Wednesday.

In developing the Chicago Energy Use Benchmarking & Transparency Ordinance, city officials reached out to eight U.S. cities that have enacted similar benchmarking legislation and adopted the best elements of each program.

During a panel discussion at BD+C's BUILDINGChicago conference this week, Jamie Ponce, Chicago City Director of the C40 - Clinton Climate Initiative, outlined the elements that differentiate Chicago's benchmarking ordinance. The most unique element, said Ponce, is a rule that mandates the verification of building energy data every three years. The data must be checked and verified by a registered architect, professional engineer, or other trained professional designated by the city. Chicago will be the only city with such a mandate.

"We asked representatives from the eight other cities what they would add or do differently, and the overwhelming majority mentioned the need for data quality and accuracy," said Ponce. "They said they were getting some questionable data from building owners."

Causes range from errors in data entry to owners not fully considering all aspects of the building in calculating the energy performance. "It's helpful to have an additional data check," added Ponce. The city will offer low- and no-cost verification options for building owners who cannot afford third-party data verification services.